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TRIUMFCanada's National Laboratory for Particle and Nuclear Physics
E-929 (Guelph, Michigan, SFU, TRIUMF)
Funding: NSF-Focus Center, DOE, NRC (TRIUMF), NSERC
Spokesmen: Tim Chupp & Carl Svensson
Eric Tardiff, Tim Chupp, Wolfgang Lorenzon, Celia Cunningham, Jan Zirnstein (Michigan) John Behr, Matt Pearson, Gordon Ball, Greg Hackman, Scott Williams, Adam Garnsworthy,
Jamie Kilkenny, Martin Djongolov (TRIUMF)Carl Svensson, Paul Garrett, Smarajit Tirambak, Chandana Sumithrarachchi (Guelph)
Mike Hayden (SFU)
Radon-EDM Experiment
S-929 has been given Stage-2 approval in December 2007 for 32 shifts ofEDM experiment development with 121/123Cs.
+
-
+
-
P or T+
_
gd > 0 gd < 0
Atomic Electric Dipole MomentSeparation of Charge along J: <d>=gd<J>
EDM MotivationsUndiscovered
Study CP violation: mass scaleSignal of NEW PHYSICS (beyond SM - CKM)
Cosmological Baryon Asymmetry
<d> = e<r> = e ∫ rρ d3r
We measure gd <J•E> .E
if T is a symmetry, gd=-gd
d=e r <d> = gd<J>
<r> = ___ <J>gde
EDMs and New PhysicsCKM CP violation nearly vanishes
New Physics (or θQCD)Phases
ηqqgπNN
QSchiff datom
• Neutron, electron and Schiff are complementary• Even upper limits are important
EDMs and New PhysicsCKM CP violation nearly vanishes
New Physics (or θQCD)Phases
ηqqgπNN
QSchiff datom
Octupole Deformation-Parity Doublets(see Feynman vol 3.)
NH3
|b>
|a>
|ψ±>= ____ ( |a> ± |b> ) 1√ 2
S ~ <+|ηr3cos θ|-> ~ ηβ2β23ZA2/3r0
3
E+ - E- E+ - E-
β3
E J---
++++
-- -
Nuclei with Octupole Deformation/Vibration(Haxton & Henley; Auerbach, Flambaum, Spevak; Engel et al., Hayes & Friar, etc.)
S ~ <+|ηr3cos θ|-> ~ ηβ2β23ZA2/3r0
3
E+ - E- E+ - E-
Ref: Dzuba PRA66, 012111 (2002) - Uncertainties of 50%*Based on Woods-Saxon Potential† Nilsson Potential Prediction is 137 keV
E J---
++++
-- -
NOTES:Ocutpole EnhancementsEngel et al. agree with Flambaum et al.Even octupole vibrations enhance S (Engel, Flambaum& Zelevinsky)
Nuclei with Octupole Deformation/Vibration(Haxton & Henley; Auerbach, Flambaum, Spevak; Engel et al., Hayes & Friar, etc.)
S ~ <+|ηr3cos θ|-> ~ ηβ2β23ZA2/3r0
3
E+ - E- E+ - E-
E J---
++++
-- -
βdecay Studies of Rn Structure8 π @ TRIUMF
- Very high-level density in the odd-A Rn isotopes within the β decay Q-valuewindow
- Many/most of the transitions will be highly converted.
- Long chain of radioactive daughters requires flexible collect, count, move, cycles.
- In this environment a γ-ray or electron singles spectrum is of little use inestablishing structure/(i.e. a decay scheme).
- High statistics β: γ-γ, γ-e, e-e are required
- The 8π Spectrometer at ISAC is certainly the world’s best facility for such studies.
- Timeline Issues: At beams at ISAC – 2010 (2008?) + 1 year for analysis (meets start of RadonEDM)
Why 223/221Rn?• Octupole vibration or deformation enhancement.
• Long(er) half-life
• EDM measurement in cells (see 129Xe)
• Co-magnometer measurement
P or T+
_
gd > 0 gd < 0
Atomic Electric Dipole Moment - Techniques
B E
2µ.B-d.E
Precision: (σd)-1 = 4EΓ−1 (S/N)
S/N =√ A2 NRnT2RF powerB homogeneityE- E+
Γ
-1.0
-0.5
0.0
0.5
1.0
signal (v
olt
s)
2.01.51.00.50.0
time (µsec)
Δω
Polarize RF pulse Measure Polarize RF pulse Measure … x50 E+ E- … E+ E- E0 E- E+Collect
Spin-Exchange Optical Pumping
• Optically pump the Rb withcircularly polarized laserlight.
• Spin-exchange collisionstransfer the polarization tothe radon nuclei.
Buffer gascollisions
1/2 1/22/3 1/3
5s1/2
5p1/2
ms=-1/2 ms=+1/2
Rb
Rb
223Rn
223Rn
Binary Collision:τ~10-12 sec.
Rb
Rb
223Rn
223RnN2
N2van Der Waals
Molecule:τ is dependent on
3rd body (N2) pressure.
Gamma Ray Anisotropies
• Polarized nuclei emit gamma rays withcalculable directional distributions.
!
W (") =1
4#1+
3
2 ji(2 ji $1)mi
2ami
$1
3ji( ji +1)
mi
%&
' ( (
)
* + + P2(cos")
,
- .
/ .
0
1 .
2 .
jf=ji-1 pure dipole transition
jf=jijf=ji+1
δ
(W(0º)-W(90º))/(W(0º)+W(90º)) for jf=ji+1
W(θ) W(θ)
θ θ
δ δ
1234
56
7 8
8-Trigress/Griffin detectorsMagnetic Shielding
(Active + Passive)
cell
Mu-metal
Active shield
1
23
4
5
67
8
This shows schematically the secario ofpulling the detectors back. Magnetic Shielding
(Active + Passive)
cell
Mu-metal Active shield - 3 dimensions
1 mGmagnet
BGO compton supressors
14x103
12
10
8
6
Counts
per
bin
6050403020100
Time (s)
12x103
10
8
Counts
per
bin
201816141210
Time (s)
12x103
10
8
Counts
per
bin
201816141210
Time (s)
Gamma Anisotropy (A=0.2 0.1) T2 = 30 s E=5 kV/cm
We only need beam 10% of the time
Statistics Limited by Tigress Count Rate
Beta Asymmetry
• No count rate limit (current detection mode)• Discriminate species only by frequencies• Scattered betas (lower effective A, Background)
Progress
• Noble gas collection with 120Xe• 209Rn polarization and relaxation at Stony Brook• ISAC Floor space• EDM cell development• Tigress delivery• Increaseing work-load and collaboration
120Cs (30 keV)no radon at TRIUMF yet
1. Bombard foil2. Heat foil: release to target chamber3. Freeze to cold finger4. PUSH to cell (buffer gas)
Maximum efficiency: εmax=75%
Progress: High efficiency tranfer of 120Xe at TRIUMF: from millstones to milestones
209Fr (50 s)197Au
heating
~100 MeV
16 O5 kV
1. Make 209Fr and implant in foil2. 209Fr (50s) _> 209Rn (28.5 m)3. Heat foil: release to target chamber4. Freeze to cell5. Get about 500,000 209Rn in cell
HPGe2
HPGe1
Studies with 209Rn@ Stony Brook
Laser:LDA
209Rn (28.5 m)160
140
120
100
80
60
40
20
0
800700600500400300
600
500
400
300
200
100
0
800700600500400300
337 keV
408 keV
511 keV
689 keV745 keV
After transfer~ 500,00 209Rn
Before transfer
The 209Rn Decay Scheme
(7/2)-
7/2-
7/2-
9/2-
1097.64
5/2-
209Rn
209At
0
745.78
408.33
1%
44%
15%
E.C.
γ-ray Energy Intensity δ (Mixing Ratio) 337.45 14.5 ∞ 408.32 50.3 0 689.26 9.7 >3.57 745.78 22.8 >2.86
!
" 2 =a1
2
a2
2
!
a1 =1" pure dipole
a2 =1" pure quadrupole
require : a1
2+ a2
2=1
from Table of Isotopes
Modeling Polarization• Quadrupole relaxation should be the dominant mechanism.• As a first approximation, set Γ1=0, calculate γSE for a given
T, and calculate the expected anisotropies.
W(0º)/W(90º) W(0º)/W(90º)
Γ1 Γ1Γ2 Γ2
jf=ji+1 jf=ji
Modeling Polarization• Can calculate the expected
angular distribution of gammarays as a function of spin-exchange and relaxation rates.
• The spin-exchange rate γSEdepends on the Rb density,which depends on celltemperature.
• The dipole and quadrupolerelaxation rates, Γ1 and Γ2,must be determined from data.
-5/2 -3/2 -1/2 1/2 3/2 5/2
1/7γSE 8/35γSE 9/35γSE 8/35γSE 1/7γSE
1/21Γ1 8/105Γ1 3/35Γ1 8/105Γ1 1/21Γ1
1/35Γ2
1/28Γ2
9/140Γ2
1/14Γ2 1/35Γ2
1/28Γ2
1/14Γ2
9/140Γ2
!
"2(T) = "
2
#e$E / kT
Spin Exchange Pumping
Laser Intensity Profile
Optical pumping rate
Rb polarization
Absorption Rate
Spin destruction rate
Gas concentration
Radon polarization Total magnetic moment
Pressure broadening
Spin Exchange Rate
Buffer gas concentration
Rb Concentration
RadiationTrapping
radon relaxation (quadrupole)
EDM Cell DevelopmentWe want a single cell @ 200C
Problems: leakage currents, materialsSilica (Fused Quartz) or Sapphire
IN PROGRESS (Celia Cunnigham)
Backgrounds
Build-up of decay products for γ-anistropy probe Change cells (weekly?) - good for systematics
Scattered betas (beta asymmetry detection)
σω = ___ ______ = ____ ________________ 2 1 2 1 T2 (S/N) T2 √ A2(1-B)2Nγ
SystematicsLeakage currents -- must be minimized: Multiple species
Electric quadrupole moment (gradients/walls)Change cells, cell shape/orientation: Multiple species
Electric field effects on shields, electronics, etc.Check and measure with E=0E2 and |E| effects (Stark shifts)
Multiple Species: J=1/2, 3/2, etc.Motional effects <vxE> (negligible in gas cells)
Δ
SystematicsLeakage currents -- must be minimized: Multiple species
Electric quadrupole moment (gradients/walls)Change cells, cell shape/orientation: Multiple species
Electric field effects on shields, electronics, etc.Check and measure with E=0E2 and |E| effects (Stark shifts)
Multiple Species: J=1/2, 3/2, etc.Motional effects <vxE> (negligible in gas cells)
Δ
Comagnetometers
• Long lived; produced in gobs; noble gashω = 4(dE + µB)•J + Q EJ2 + …
Cold finger
133Xem N2
Beam Line
Schedule
Measure Rn nuclear structure (8-π)First RADON EDM measurements 2011
32 shifts approved for 2008-9+ August 1-4 (8 shifts): Collect and polarize 121.123Xe (from 121,123Cs) (J121=5/2; J123=1/2)
Laser, simple magnet (ala Stony Brook)
+ 6-12 months (8+ shifts): Measure free precession (DAQ, good magnet, 2+ Tigress modules)
+ 6-12 months (16 shifts): EDM trial run with 121Xe (EDM cell, laser development)
2010: Actinide Target
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